At the beginning of his Commentary on Aristotle’s Physics II.2, Simplicius attempts to reveal the principal meaning of physis, that which in his view is preeminent above all others presented by Aristotle in Physics II.1. Through the arguments he uses to show what the principal meaning of physis is, we are also able to better understand the other meanings. These other meanings are, on the one hand, those which can be indisputably traced in the Aristotelian text itself, and on the other, those which are discovered in the light of Simplicius’ insightful reading of it. Simplicius appears to recognize—or at least to be conscious of the fact—that this part of his Commentary constitutes an autonomous analysis and explanation of the different meanings of physis, which sets out to reveal its concealed principal meaning. My aim in this paper is to show that in his comments on Physics II.1, Simplicius is trying to offer an exegesis of the Aristotelian arguments, while in his comments regarding the beginning of Physics II. 2, he proceeds to a bold reading of what Aristotle has said in chapter one. He does this by giving his own interpretation of the meaning of physis, within the frame which Aristotle had already sketched out in the previous chapter, but also by deviating to some extent from Aristotle. For Simplicius the principal, albeit concealed, meaning of physis, within the Aristotelian philosophical framework, lies in the idea that nature is a sort of propensity for being moved and a sort of life, to wit, the lowest sort of life (eschatē zōē).